Epidermal-Dermal Interactions in Normal and Diseased Adult Human Skin. The purpose of this study is to define the control cues from dermis which influence epidermal growth, maturation and organization utilizing a model in which recombinants of isolated epidermis and dermis are cultured for short periods on the chick chorioallantoic membrane (CAM). In this system, dermis or a connective tissue is required for epidermal maintenance. One approach will be to construct dermal substituted of known composition to be tested for their ability to maintain epidermis. Another approach will be to selectively manipulate dermis and to test the altered dermis for its ability to maintain epidermis. We have established a similar model for long-term cultivation of adult human skin on nude athymic mice and utilized the system for the confirmation of CAM studies as well as for the study of epidermal-dermal interactions in lamellar ichthyosis. We plan to study other types of ichthyosis and psoriasis in this system. Formation of Structures at the Epidermal-Dermal Junction in Normal and Diseased Human Skin. Studies will be done to selectively extract structures at the epidermal-dermal junction (basal lamina and anchoring fibrils) in order to attempt their isolation, purification and characterization. Using a model devised for the study of basal lamina and anchoring fibril formation in normal adult human skin, selective inhibition of basal lamina and anchoring fibril formation will be used to determine information regarding the nature of these structures.